The storage capacity of memory devices has remarkably increased along with an increase in the degree of integration and the number of layers of semiconductor devices, for example. This is implemented by the progress in microfabrication technology. On the other hand, the chip size has increased in spite of an increase in the number of layers and the like. Moreover, the number of production steps has increased along with microfabrication to increase the chip cost. In such a situation, chemical mechanical polishing technology has been used to polish a processed film and the like, and has attracted attention. Microfabrication technologies such as planarization have been implemented by applying the chemical mechanical polishing technology.
Shallow trench isolation (STI) technology is known as such a microfabrication technology, for example. The STI technology utilizes chemical mechanical polishing in order to remove unnecessary insulating layer deposited on a wafer substrate. Since the flatness of a polishing target surface is important in the chemical mechanical polishing step, various abrasive agents have been studied.
For example, JP-A-5-326469 and JP-A-9-270402 disclose that the polishing rate in the STI chemical mechanical polishing step is increased using an aqueous dispersion utilizing ceria as abrasive grains while achieving a polished surface with a relatively small number of scratches.
In recent years, a further increase in yield and throughput of semiconductor elements has been desired along with a further increase in the number of layers and a reduction in line width of semiconductor devices. Therefore, chemical mechanical polishing technology which substantially does not produce scratches on a polished surface and achieves high-speed polishing has been desired.
The number of scratches on the polished surface is effectively reduced using a surfactant such as chitosan acetate, dodecylamine, or polyvinylpyrrolidone (see JP-A-2000-109809, JP-A-2001-7061, and JP-A-2001-185514, for example). However, since the polishing rate decreases when using such technology, an increase in throughput has not yet been achieved.